In its original form, the scapular is a part of the monastic habit (the outfit that monks wear)…

Today, the term is used most often to refer to a sacramental (a religious object) that has essentially the same form as the monastic scapular but is composed of much smaller pieces of cloth (usually only an inch or two square) and thinner connecting strips. Technically, these are known as the “small scapulars” and are worn by lay faithful as well as those in religious orders. Each small scapular represents a particular devotion and often has a certain indulgence or even a revealed “privilege” (or special power) attached to it.

…Those who wear it faithfully as an expression of devotion to the Blessed Virgin Mary, it is said, will be granted the grace of final perseverance. More